T-Mobile on Tuesday held a press conference to introduce the first mobile handset based on Google’s Android platform — the G1, which will retail for $179 when it goes on sale at select T-Mobile outlets and third party retailers on October 22nd.

The G1 (official website) includes a built-in compass, a 3-megapixel camera, a touchscreen that slides open to reveal a full QWERTY keyboard, and a trackball for more precise, one-handed navigation. The device will come SIM-locked to T-Mobile, with built-in support for the carrier’s 3G and EDGE network as well as Wi-Fi.

Among the G1’s software features is one-click contextual search that allows users to search the entire device with the touch of a finger, and version of Google’s new Web browser called Chrome Lite that presents web pages in their natural form and lets users zoom in to expand any section by simply tapping on the screen.

All the Google Android hype just might be true: T-Mobile’s first Android-based phone is expected to be revealed next week and in stores by next month.

Invitations leaked around the Web indicate the heavily anticipated T-Mobile Dream will be unveiled and demoed at a media-only event in New York next Tuesday, September 23. The HTC-manufactured phone should then become widely available by the end of October, according to the Wall Street Journal. Despite all the talk of delays, then, that date would put Android right on target with its initial timetable.

Of course, what sets Android most apart from Apple’s offering may be its open nature. Particularly given the rage over iPhone apps being banned over the past several days, Google’s user-moderated Android Market—in which any developer can register, upload, and publish within minutes—is sure to grab attention. The site, Google has said, will emulate YouTube’s community voting system for content. No company officials will interfere or “ban” app submissions.

Pricing hasn’t officially been revealed, though Web-based reports put the tag around $400 for the Dream, with contracted specials rumored to become available for closer to $150. More than 600,000 units are said to be under preparation for shipping.

Google, meanwhile, showed off a non-specific phone running the software at a closed developers’ event in Europe Tuesday. People in attendance say the device looked eerily similar to the T-Mobile Dream, though Google would not confirm or deny the branding. (Pieces of masking tape were placed over any indicating signs.)

It’s been a long road for Android — and while it may not have hit the finish line first, the mobile world is no doubt keeping an eager eye on its final stretch. So will Google’s gamble pay off? We’ll find out soon enough.